The present invention is generally directed to fuel cell components and a method of operating the same, and to solid oxide fuel cell anode materials in particular.
In a high temperature fuel cell system, such as a solid oxide fuel cell (SOFC) system, an oxidizing flow is passed through the cathode side of the fuel cell while a fuel flow is passed through the anode side of the fuel cell. The oxidizing flow is typically air, while the fuel flow can be a hydrocarbon fuel, such as methane, natural gas, pentane, ethanol, or methanol. The fuel cell, operating at a typical temperature between 750° C. and 950° C., enables the transport of negatively charged oxygen ions from the cathode flow stream to the anode flow stream, where the ion combines with either free hydrogen or hydrogen in a hydrocarbon molecule to form water vapor and/or with carbon monoxide to form carbon dioxide. The excess electrons from the negatively charged ion are routed back to the cathode side of the fuel cell through an electrical circuit completed between anode and cathode, resulting in an electrical current flow through the circuit.
The high temperature SOFCs are normally operated with significant excess fuel flow because (1) most present day anodes suffer partly irreversible damage when exposed to high oxygen partial pressure (very wet fuel); and (2) the electrochemical driving potential at high utilization (wet fuel) is relatively small and therefore current densities become small. Recently, anodes have been developed which are oxidation resistant. However, these oxidation resistant anodes usually display rather poor performance characteristics.